YOF nano/micro-crystals: morphology controlled hydrothermal synthesis and luminescence properties
Uniform YOF nano/micro-crystals with nanosphere and micro-rod morphologies have been synthesized by simply modulating the pH values of the initial solution through a facile hydrothermal route without using any morphology controlling agent. The possible formation mechanism of the micro-rods has been proposed based on a series of time-dependent experiments. XRD, FT-IR, TG-DTA, Raman spectra, SEM and TEM, as well as down-conversion (DC) luminescence (photoluminescence, cathodoluminescence) and up-conversion (UC) luminescence spectra are used to characterize the resulting YOF samples. The results of the DC and UC luminescence properties prove that the as-synthesized YOF are excellent host lattices for rare earth luminescence. Among the different morphologies, YOFs with a micro-rod morphology present the strongest luminescence intensity which may be due to the larger size and the fewer quenching sites, confirmed by the results of morphology-dependent luminescence intensity.